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astroengine writes "By focusing the Green Bank radio telescope on stars hosting (candidate) exoplanets identified by NASA's Kepler space telescope, it is hoped that one of those star systems may also play host to a sufficiently evolved alien race capable of transmitting radio signals into space. But in a study headed by ex-SETI chief Jill Tarter, the conclusion of this first attempt is blunt: 'No signals of extraterrestrial origin were found.' But this is the just first of the 'directed' SETI searches that has put some very important limits on the probability of finding sufficiently advanced alien civilizations in our galaxy."

Maybe all of the other aliens are smart enough to prevent the radio waves of their versions of Jersey Shore (and other cruft) from spilling out into space. Maybe we're the only dumb ones that let it happen. We're probably the laughing stock of the galaxy...

Anthropic principle: we can only be searching for Aliens in spaces/universes where they do not exist.If they did exist in our part of the universe we'd be dead already.(If they were friendly, they'd have been wiped out already by another race that is not.)

Default fallback programming: "I Love Lucy".They have had plenty of time to develop cloaking technology against our mind destroying Weapons of Mass Broadcast. We have terrified the galaxy within a 60 light year radius, pedant.

We NEVER thought the sound barrier was impossible to break. We thought it might be impossible at the time to build an aircraft that could handle the structural stress with the materials available at that time. We knew the sound barrier could be broken--bullets had been breaking it for decades. The two are NOT comparable in any way.

Radio signals can deattenuate with range, other aliens might not be running a SETI program (and therefore glowing in the sky because they transmit stuff to random stars), they might be much further away and so their signals haven't reached us yet. The universe is enormous, no doubt there's *someone* out there.

Quite the assumption on alien life forms using radio waves, but I guess as a civilization we gotta start somewhere with the search. Or, we can follow the sci-fi model and colonize worlds UNTIL we find alien life. The latter makes more sense in a lot of ways. I'm going to go think of a profit model for colonization now.

"... it would only be "quite the assumption" to believe they use it exactly like we do."

Right. But that assumption isn't really made. SETI At Home, for example, essentially does Fourier analysis on signals, looking for patterns. While they may not use it as we do, having patterns in the signal is a pretty safe assumption. Or to perhaps be more accurate: we don't know of a way to look for signals that do not exhibit patterns.

The profit model is simple enough once the profit no longer has to be made on earth. In short, there's a chicken/egg problem. Colonization makes sense if you'll be richer when you move to the colony than you are now on Earth (this is what has ALWAYS driven colonization throughout history). Right now we assume you'd be richer on Earth than you are now post-colonization. That is probably not possible in the near future (resource transfer between planets isn't practical). Getting to where you can become r

Quite the assumption on alien life forms using radio waves, but I guess as a civilization we gotta start somewhere with the search. Or, we can follow the sci-fi model and colonize worlds UNTIL we find alien life. The latter makes more sense in a lot of ways.

One of these things we can do right now, the other hasn't even been proved to be humanly possible yet.

The problem with colonizing is basically the radiation in space pretty much kills everything given the time frames involved at sub-light speeds..

Uh, the answer to radiation in space is... shielding. If you're building a colony ship you can live in for a century while traveling between stars, the mass of required shielding will be small compared to the mass of the ship.

Shielding is pretty much all about mass. You need boat loads of mass to make an effective enough shield to survive in space for very long. You can use water, but you need to get it into space (or find it someplace already in space), then climb inside and get all this mass heading in the correct direction (burning fuel or something) fast enough you don't die before you get there, then slow down all this mass so you can stop someplace (more fuel). All this amounts to HUGE amounts of mass..

The belief in extraterrestrial life is at least based on the observation that life exists on Earth, and the number of stars and planets like our Sun and Earth in the universe is.. astronomical.

The belief in God has no such basis.

I think the belief in extraterrestrial life is primarily based in the disbelief in God. If there is no other life, then we are special. If there is no God, we are not special. Hence, if there is no God, there ought to be extraterrestrial life.

I believe in God and I believe in extraterrestrial life. It's not an either/or proposition. I also believe that any knowledge we can gain by experimentation or investigation brings us closer to God. My belief in God is based on personal experience. Anybody who cares to find out for himself can repeat the experiment and get his own results. It's a non-trivial experiment, and you won't find it reported in Science. But it is reproducible.

My belief in extra-terrestrial beings is much closer to "blind faith" t

Yes. The idea that life could evolve in the same way it did here somewhere else in the galaxy with similar conditions is just as looney as believing in a sky wizard who hates homosexuals and loves killing brown people, who believe in another, but different sky wizard who likewise hates homosexuals but loves killing white people, and each sky wizard claims that the other is a false sky wizard, although they both agree that the world is 6,000 years old. Yeah, those two things are both completely the same. You sure delivered a convincing argument there.

IS not scientific proof of anything. Often science is found where statistics fails. In other words... Science is just as often found in the "that is odd" moments, that lie outside of what statistics suggest. Statistics is math, math is used in science, but math is not science. Math is just a tool.

Well, suppose hypothetically there is another civilization that reached the point we are at now over 100,000 years ago, and they happen to reside near a star that is a million light years away. In such a scenario, we won't hear a peep from them for another 900,000 years.

The only other possibility is that they use some form of communication that is faster than light, which would mean they are using something other than EM based communication. EM based communication is all that we have the capability of looking for.

Due to the sheer size of the known universe, it is inevitable that there is sentient life beyond earth. Even if what we have here is merely a pattern of chemicals, that pattern is bound to have repeated elsewhere, if not identically then very similarly.

We already have non-human sentient life on our planet - many cetaceans are sentient - but we are utterly unable to recognize it. The only sentient life humans will actually recognize, are the ones that carry bigger guns than ours. Sad but true.

Due to the sheer size of the known universe, it is inevitable that there is sentient life beyond earth.

[citation needed]

Yeah, it's possible that there are other creatures like us in other galaxies, but our galaxy appears to be a wilderness. Since we could colonise it within ten million years, that's a pretty good sign that there aren't any others here.

No need for faster than light tech. They could as we are now moving on to digital transmission modes that use less power and are harder to detect. Maybe they use fiber optics for all fixed communications with a wide network of relatively low power cells for most mobile. Even satellite communications may be relatively low power. Such a system would be rather hard to detect across light years.

"The Universe is big and old and rare things happen all the time, including life."Lawrence Krauss (I think).

You'll have to forgive me for deferring to the judgement of someone who has more of a chance of grasping just how big and old the Universe really is*. There are about 300 billion stars in our galaxy alone; to think that only one of them will ever warm a life bearing planet seems absurd... but then again that's a leap of faith too, even if it is a somewhat smaller one.

If the odds of winning are 1 in 1 million (round numbers are easier, and past about 1 in 1000 with 1000 tickets the odds are asymptotic anyway), then the chance of not finding a winning ticket in the first million tickets purchased is 36.8%. Which means you only have a 65.2% chance of winning with 1 million tickets and a 1 in 1 million chance on each ticket. Not even close to 100%.

Isn't that wrong because you're ignoring how lotteries usually operate, which is to pick a winning combination out of a limited set. For your example if the lottery ticket consists of a player chosen number from 000000 to 999999 and the winner is decided by picking a random number from 000000 to 999999, then there is a 1 in 1 million chance of a single ticket winning. However if you buy 1 million different tickets then you have every single possible combination, so your chance of winning is 100%.

It's probably going to happen in the opposite order. I bet we'll know the inevitability of life, long before we ever know where our life came from.

Someone will create conditions where a new tree of life can spontaneously start, or else we'll find a different independent already-existing one. Meanwhile, all traces of our own tree root will still be three-billion-years eroded/eaten.

More likely they've figured out either a more advanced communications technology than radio, or have gone to tightbeaming for long distances. Or they, like us, aren't putting out any signals that get beyond a couple of light years.

What more advanced communications technologies are there without altering the laws of physics? On one hand, those who speculate on , overunity energy which requires undiscovered physics are called lunatics, and yet, people freely speculate that there is undiscovered physics for a non radio communication system.

Yes, I'm of the opinion that science, technology and engineering will continue to advance long after I'm gone, probably to heights I would struggle to comprehend just as a visitor from the 18th century would struggle to understand what we've achieved, and as such feel comfortable indulging in speculation. It's deriding such speculation that is indicative of an unscientific mind.

In all likely hood, they would come to colonize the Earth since it is the perfect distance to the host star to support liquid water and an existing ecosystem that isn't dependent on any one species that would resist colonization.

So they're going to burn more energy than the human race has used since the beginning of time to come here and colonize Earth, when they could just dismantle a planet in their own system and build a Dyson sphere?

The only thing Earth has that aliens couldn't find elsewhere is Earth life. And after all that cattle mutilation and anal probing, they should have plenty enough DNA to rebuild that wherever they want to live.

Without knowing either the technology for interstellar travel, or the motivations of an alien intelligence its difficult to figure out why they might want our planet. The might simply like planets, and not care that someone else was there first. They may be motivated by religion to convert all sentients to their own beliefs. Large scale planetary modification may be more difficult that interstellar travel: Its pretty easy to imagine technology to get to 0.1C (even fission rockets could do that). A millio

But if we apply the razor and consider that there might just be a difference in perspective [youtube.com], I think we can all agree on the following: The universe is only very big because we are very small.

As soon as we stop thinking of aliens in terms of human scale and desire and capability, things become a lot more mundane: Chances are excellent that even if other intelligent life does exist out there, we're either far too big or far too small to both

Says who? What if the asteroids are the remnants of a life bearing planet that was ripped apart? What if there has been microbial life on them since they were formed? We don't know, and until we do a significant on-site survey of the asteroid belt, we won't know.

Having a whole bunch of radio signals emanating from your planet is like saying "rob me! rape me! kill me!" to any wandering castoffs from alien civilization.

It's more like saying that while penniless and surrounded by mountains of gold. Anyone capable of interstellar travel has easier access to anything we have to offer than invading a planet and boosting it up from the surface (more likely the bigger factor). There's more usable metal in the trojan asteroids around Jupiter than all that humanity has dug up in its history. More water in the cometary halo and various moons than could conceivably be cost efficient to boost into orbit from the Earth's surface.

A really good point. There is a strong argument that the first thing you should do on detecting an alien civilization is to attack with stealth R-bombs (or substitute your favorite interstellar weapon). Of the possible outcomes:

1. they were hostile: you got them first, you win!

2. They were incredibly more advanced than you: The attack will seem cute to them, sort of like a kitten pouncing you your toes. Maybe they will post pictures of you on their tentacle-book site.

The non-aggression principle is universal morality, more than likely. Any species that violates it is likely to tear itself to pieces before it builds its first warp drive. Conversely, any species that builds warp drives is much, MUCH more likely to be peaceful. Your only real wild cards are weird communal mind species or those with otherwise utterly and Earth-unprecedented but robust methods of thought/existence.

In #2 I meant a LOT more advanced. When I was hiking in the Canadian Rockies a Pika (small fluffy rodent) jumped up on a rock and started squeaking at me. It was acting at its most threatening trying to scare off the invader. It was adorable and we took many pictures.

Its not clear that a peaceful society will develop the sort of high energy technologies that are probably need for space. They might instead develop a low energy sustainable technology that lets a modest size population live happily on the limi

Oh I wouldn't worry about that. We've only had radio for less than 150 years. How many stars are there within a 150 ly radius? By the time the very first signal from Earth reaches the center of the galaxy, the human kind may have long destroyed itself.

Unless earth is much more exceptional than what we think there is hard to imagine reasons for robbing or killing us.

If FTL travel is possible and there are advanced civilizations somehwere I find it more likely that they'd just ignore us. Perhaps there are literally billions of planets out there that are inhabited by mostly harmless, boring little monkey-like creatures.

Distance between stars, round trip, and power of the signal you have to send to a particular planet, point of time in civilisation development.... So many obstacle as to make communication improbable and a waste of time and resource (remember we are only *hearing* , *sending* is much much more costly especially when you do not know where you have to send to and how far, we have only 2* a few minutes signal we sent which went further away than a few light years 8back in the 70) all other radio/radar/tv they

... to think that anything in line with typical-strength radio broadcasts (and which were not being specifically directed out towards the stars for an attempt to send an interplanetary signal) from a distant planet would have any chance of being decipherable from background noise if the origin of such a signal were even as near as the closest star?

unless this search could detect broadcast type terrestial signals that radio stations use, these studies are not a sure way to discount the idea of ET civilisations on planets, in fact, they do not, as the number of civilisations with TV and Radio broadcasts terrestrially, but have decided its not a good idea to broadcast ridiculously powerful signals that could be heard light years away, is probably very large.

My point was that even *WE* don't typically broadcast signals of sufficient strength to even be distinguishable from background noise only as far away as the nearest star, much less any further, unless we very specifically intend to. So unless an alien civilization somewhere out there were actively trying to send signals to the stars, we aren't ever going to discover them with SETI. Period.

The tighter they are, the less likely you are to be in the path of the transmission. Plus, the Earth is a moving target, so you might only cross the path of the transmission for an instant... while your antenna is pointed in the wrong direction.

Actually, we don't do much directed broadcasts so even that is a stretch. Less than a couple dozen directed transmissions so far that would actually be detectable when they reached their destination. Only one of those has reached its destination, and even if there happened to be aliens living there (which seems even less likely given what we've learned about the star since then) we wouldn't have heard a response back yet.

And any signal we might detect would have most of its entropy shifted to the main signal block, followed by a little orderly decryption section, which to us, would also look like noise, so running your signal though a zipf analysis probably wouldn't work.

Frankly, I think the radio thing is a bit silly. The detectable radio interval for any civilization is likely to be quite short. Even we're moving to photonics wherever possible. We'd probably do better looking for light signals, or astronomical star sized objects that look like artifacts, or creating large area Casimir antennas in space capable of detecting wide area, coherent changes to virtual particle activity.

One thing to take in to consideration is which of the 86 stars they pointed at and their distances from us. As long as they stuck to star systems in the Milky Way galaxy, all this really says is that other planet didn't have the capability to transmit radio frequencies up to 75,000 years ago (considerably longer for systems outside our galaxy). Considering we just got the capability only 107 years ago, if any alien race is roughly on par with our origins, speed of evolution, and technology advancement, we

And if they had something better than Radio or Light, then why would they use inefficient slow tech?

Scientists are discovering physics and material hacks all the time, so the possibility of "instantaneous" communication is growing stronger. University labs are producing some interesting results that seem to skirt along the edges of information theory and quantum theory. It's unlikely, but possible. Check back in a hundred years or so...

And even if they're just using radio if the signals are highly compressed (or encrypted) they'll be indistinguishable from noise. Different noise than the background, but still not data.So it's not the interval between a civilization discovering radio and discovering some more advanced technology that matters, it's the interval between the discovery of radio and the discovery of sufficiently advanced compression techniques.

And if they had something better than Radio or Light, then why would they use inefficient slow tech?

Precisely so we could detect it. If they do have such better tech, then we are probably so far behind them that we're not even worth conquering, let alone being a possible market, or intelligent equal. They could be broadcasting such message specifically to help us up to a higher level or the more efficient tech, ether out of some sense of an "advanced alien's burden", simply getting us to a point they could exploit us, or so we could signal back and they could come knock out the competition. Science FIctio

Dr. Hugh Ross theorizes that we humans are at the earliest possible time intelligent life can exist in the Universe. So regardless on what you think on how we got here, it may not be possible for other intelligent physical life to have existed before us humans. Since reality is only 14.7 billion years old this is a plausible explanation.

Quote: "Instead, plasma cosmology assumes that, because we now see an evolving, changing universe, the universe has always existed and always evolved, and will exist and evolve for an infinite time to come." ( http://www.bigbangneverhappened.org/p13.htm [bigbangneverhappened.org] ; )

That is, we believe (have faith in) the correctness of the most popular current set of theories, though we probably know nothing.

Fact:The largest single aperture radio telescope in the world is the Arecibo Observatory.It's maximum power output at 2380 MHz is 20 TWIf a matching radio telescope were placed on a planet orbiting our nearest star Alpha Centauri (4.2 light years away) and broadcast at full power, directly at earth... the signal would be too weak by the time it arrived for Arecibo to detect it.

We can't even detect our own radio signals with the best equipment we have at interstellar distances. I think it likely that we'll be well out of the radio age by the time we can... The fact that the sky isn't flooded with alien Television stations isn't because there are no aliens, it's because there's a better way to transmit that we haven't figured out yet.

Fact:
The largest single aperture radio telescope in the world is the Arecibo Observatory.

True

It's maximum power output at 2380 MHz is 20 TW

Not quite true. The 20 TW is what it would take to create istropic radiation of equivalent power to the beam, when Arecibo is operating as a radar.The actual power transmitted is much less, and the return signal is hemispherically isotropic, which is what limits the radar range.

If a matching radio telescope were placed on a planet orbiting our nearest star Alpha Centauri (4.2 light years away) and broadcast at full power, directly at earth... the signal would be too weak by the time it arrived for Arecibo to detect it.

This is complete bullshit. Arecibo could talk to a similar capability radio telescope a thousand light years away. ( If you put a 20 terawatt transmitter on it you could probably talk to Andromeda if you didn't melt the reflector first.)

Unless they are deliberately aiming a signal at us, we wouldn't be seeing anything. Even regular analog transmissions are impossible to see at this distance. And modern radio signals (cellular, encrypted, compressed) just look like low level random noise anyway.

Not english speaker so was unsure if the headline was about "No transmiting aliens" found or No "transmitting aliens" found. If was the 1st alternative then was wondering how they found them if they didnt transmit anything, maybe a Ringworld, a Klemperer rosette or another non natural formation was detected.

Maybe should be considered how much power is needed to transmit something to a particular point of the sky, strong enough to hit the entire habitable zone of a solar system with enough power to be det

Draw a circle the size of a plate, then take your pen and put a dot near the rim but not too close. Say an inch.
That is the extent our radio signals have traveled if our galaxy was to be shrunk to the size of a soup pate.
Give it time, it takes about 100,000 years for our signal to get to the other side of our milky way alone. By then we would have discovered warp drive and we would have sent giant vacuum cleaners to suck up our radio signals:-)
G

"the SETI team can now place important limits on the likelihood of finding a sufficiently advanced alien race in the Milky Way. Generating a powerful radio signal requires a lot of energy, so the team point out that they will most likely detect a civilization capable of generating an isotropic signal (i.e. a radio transmission that is emitted in all directions). This would require the civilization to harness the total power output of their host star, making them a Kardashev type II civilization."

The more a signal is compressed, the more it looks like random noise. The only way you know the difference between a signal and random noise is redundancies. But redundancies represent an opportunity to save power and bandwidth, by adding compression.

The typical alien civilization has had hundreds of thousands of years to work out compression algorithms.

On top of this, spread spectrum might be used.

So what makes anyone think that SETI or anyone else would be capable of
recognizing an alien signal if the